Hydrogen　spillover　has　been　believed　to　play　an　essential　role　in　the　reaction　path　in　photocatalysis,　yet　its　rational　regulation　remains　a　considerable　challenge　for　the　design　of　highly　efficient　photocatalysts.　Herein,　hydrogen　spillover　can　be　well　regulated　at　ZnIn2S4　with　surface　decorated　by　cubic　α-MoC1-x　quantum　dots　(QDs)　with　different　lattice　strain　(ZIS/QDs).　With　the　increasing　lattice　strain　of　α-MoC1-x,　the　composite　shows　first　increased　and　then　decreased　photocatalytic　hydrogen　evolution　(PHE).　Spectroscopic　characterizations　and　calculation　analysis　indicate　that　PHE　performance　of　ZIS/QDs　is　highly　corelated　with　hydrogen　spillover　rather　than　charge　transfer　process.　Further　systematic　investigations　suggest　that　compressive　lattice　strain　uplifts　the　Fermi　level　of　α-MoC1-x　and　optimizes　the　interfacial　spillover　barrier　between　α-MoC1-x　and　ZnIn2S4,　achieving　well-manipulated　hydrogen　spillover　and　enhanced　PHE　performance.　This　work　demonstrates　a　general　design　from　the　perspective　of　lattice　strain　to　harness　hydrogen　spillover　effect　in　heterogeneous　interface　for　hydrogen　generation.　©　2025　American　Chemical　Society.